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A high efficiency on‐chip reconfigurable Doherty power amplifier for LTE communication cells
Kumar, Rajesh,Kanuajia, Binod Kumar,Dwari, Santanu,Kumar, Sandeep,song, Hanjung John Wiley Sons, Inc. 2018 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.60 No.10
<P><B>Abstract</B></P><P>In this paper, a high efficiency on‐chip reconfigurable Doherty power amplifier (DPA) with proposed topology is proposed for LTE or 4G communication cells. The proposed DPA consists of input driver topology, hybrid coupler, asymmetric amplifiers, and 1:1 balun filtered network. The proposed input driver circuit provides wide amplified signal operation within range of 2.3GHz to 6GHz with flat gain of 33 dB. The amplified signal is unsteadily divided into two paths toward the carrier and the power amplifier by 90<SUP>0</SUP> hybrid couplers and demonstrates 27.6 dB and 28.3 dB of gain along with 83.2% and 84.5% of power added efficiency at average output power of 40 dBm. The high efficiency and almost flatness in gain stability of proposed DPA providing better solution in order to overcome the interference and the broadband issues for LTE communication cells. The balun‐filtered network is employed for combined the two outputs of carrier and peak amplifiers that provides more uniform desired band of operation in the frequency responses. The proposed DPA circuit are implemented and optimized by using advanced design RF simulator platform. The fabricated chip is made by using 0.13 μm GaN HEMT on Si‐Nitride monolithic microwave integrated circuit die process. The fabricated chip of DPA provides 85% of PAE with 28 dB gain which are made close agreement with simulation results. The size of chip is 2.8*1.2mm<SUP>2</SUP> which occupies less die area as compared to existing DPAs.</P>
Parametric resonance of composite skew plate under non-uniform in-plane loading
Rajesh Kumar,Abhinav Kumar,Sarat Kumar Panda 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.2
Parametric resonance of shear deformable composite skew plates subjected to non-uniform (parabolic) and linearly varying periodic edge loading is studied for different boundary conditions. The skew plate structural model is based on higher order shear deformation theory (HSDT), which accurately predicts the numerical results for thick skew plate. The total energy functional is derived for the skew plates from total potential energy and kinetic energy of the plate. The strain energy which is the part of total potential energy contains membrane energy, bending energy, additional bending energy due to additional change in curvature and shear energy due to shear deformation, respectively. The total energy functional is solved using Rayleigh-Ritz method in conjunction with boundary characteristics orthonormal polynomials (BCOPs) functions. The orthonormal polynomials are generated for unit square domain using Gram- Schmidt orthogonalization process. Bolotin method is followed to obtain the boundaries of parametric resonance region with higher order approximation. These boundaries are traced by the periodic solution of Mathieu-Hill equations with period T and 2T. Effect of various parameters like skew angle, span-tothickness ratio, aspect ratio, boundary conditions, static load factor on parametric resonance of skew plate have been investigated. The investigation also includes influence of different types of linearly varying loading and parabolically varying bi-axial loading.
Investigation of Ionic Transport Through Track-Etched Conical Nanopores of PET Membrane
Sushil Kumar,Rajesh Kumar,Sushil Kumar,Narinder Kumar,S. K. Chakarvarti 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.1
The control of ionic transportation inside the multi asymmetric conical nanopores in polyethylene terephthalate (PET) membrane was investigated. The conical nanopores were prepared by chemical etching in irradiated PET foil using etchant (9 M NaOH) and stopping solution (1 M NaCl + 1 M HCOOH). The behavior of ionic current was recorded under stepping voltage - 2 V to +2 V at different molar concentrations of potassium halides (KCl, KBr and KI) under symmetric bathing condition in electrochemical cell. It is found that the presence of multiple ionic species and the occurrence of counterion condensation of charge regulated polyelectrolyte play an effective role in ionic current rectification (ICR). The electrical conductance of conical nanopores may be estimated by measuring the ionic current rectification properties of track-etched nanopores. The charge transport properties vary with molar concentration and pH of electrolyte. Moreover, ICR may be used as a voltage gating phenomena with wide technological applications.
Supersonic Mach Disk Characteristics in a Plasma Wind Tunnel
Rajesh Kumar Chinnaraj,Philyong Oh(오필용),Seongman Choi(최성만) 한국추진공학회 2019 한국추진공학회지 Vol.23 No.1
A primary investigation on the underexpanded flow generated in a 0.4 ㎿ class high enthalpy supersonic arc-heated plasma wind tunnel is conducted experimentally. The diameter and the position of the Mach disk from the nozzle exit is measured for overall pressure ratios ranging from 200 to 30. The empirical correlations for Mach disk diameter and position are determined which show very good agreement with experimental results.
Kumar, Rajesh,Han, Jiyou,Lim, Hee-Joung,Ren, Wen Xiu,Lim, Ja-Yun,Kim, Jong-Hoon,Kim, Jong Seung American Chemical Society 2014 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.136 No.51
<P>Activation of apoptosis, the cell death machinery, in tumor cells by organelle-specific delivery of antitumor theranostic agent is the utmost challenge in cancer therapy. Herein, we developed a highly efficient mitochondria-targeting antitumor theranostic prodrug <B>7</B> that contained two molecules of drug 5′-deoxy-5-fluorouridine and an apoptotic marker ethidium for self-monitoring intrinsic (mitochondrial) apoptosis after its activation in tumor cells. Theranostic <B>7</B> was activated by endogenously produced mitochondrial-overexpressed H<SUB>2</SUB>O<SUB>2</SUB> and released drug 5′-deoxy-5-fluorouridine and apoptotic marker ethidium to the tumor cells. The <I>in vitro</I> and <I>in vivo </I>drug release was monitored by observing the fluorescence changes of ethidium. Theranostic <B>7</B> exhibited an enhanced cytotoxicity over commercial 5-fluorouracil (an active drug of 5′-deoxy-5-fluorouridine) leading to intrinsic apoptosis monitored by in situ generated ethidium. Enhanced expression of mitochondria-mediated apoptotic genes (NOXA, PUMA, BID, BAX, and BAK), Cyt C, Caspase-3 and -9, and cell surface death receptors was observed after theranostic 7 activation in tumor cells. <I>In vivo</I> and <I>ex vivo</I> xenografts revealed that theranostic <B>7</B> significantly inhibited tumor progression and cured the tumor-bearing mice. Such organelle-specific theranostic strategies have great potential for the early diagnosis and precise treatment of cancer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2014/jacsat.2014.136.issue-51/ja510421q/production/images/medium/ja-2014-10421q_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja510421q'>ACS Electronic Supporting Info</A></P>
Controlling Mikania micrantha HBK: How effective manual cutting is?
Rajesh Kumar Rai,Madan Sandilya,Rajan Subedi 한국생태학회 2012 Journal of Ecology and Environment Vol.35 No.3
Mikania micrantha, a neo-tropical vine, is spreading rapidly in the tropical part of Nepal and is now threatening the rural ecosystem including biodiversity and rural livelihoods. However, no attempt has been made to control the spread of M. micrantha. As a result, the vines are spreading freely and rapidly. After a thorough literature review and assessment of forest management practices, we proposed a manual cutting method, as it suits the Nepalese situation for several reasons:required labor is readily available, as local communities are managing forest patches, and the method does not have any potential adverse effects on non-target native species. Experimental plots were laid out in August 2011 to examine the effectiveness of manual cutting. Two different site types based on canopy coverage were selected and divided into three blocks based on cutting strategy. Four treatments were assigned across the experimental plots following a complete block design. We harvested above-ground biomass according to the assigned treatment. The results suggested that there should be at least two consecutive cuttings within a 3-week interval before flowering, and that three consecutive cuttings resulted in 91% mortality of the vines. In addition, cutting promoted regeneration of native plant species. Employing regular cutting operations can modify understory shade enhancing regeneration of native species, which is a desirable condition to constrain proliferation of M. micrantha. Periodic cuttings reduced the competitiveness of M. micrantha regardless of canopy openness, but native ground cover should be retained.
Economic Power Dispatch with Valve Point Effects Using Bee Optimization Algorithm
Kumar, Rajesh,Sharma, Devendra,Kumar, Anupam The Korean Institute of Electrical Engineers 2009 Journal of Electrical Engineering & Technology Vol.4 No.1
This paper presents a newly developed optimization algorithm, the Bee Optimization Algorithm (BeeOA), to solve the economic power dispatch (EPD) problem. The authors have developed a derivative free and global optimization technique based on the working of the honey bee. The economic power dispatch problem is a nonlinear constrained optimization problem. Classical optimization techniques fail to provide a global solution and evolutionary algorithms provide only a good enough solution. The proposed approach has been examined and tested on two test systems with different objectives. A simple power dispatch problem is tested first on 6 generators and then the algorithm is demonstrated on 13 thermal unit systems whose incremental fuel cost function takes into account the value point loading effect. The results are promising and show the effectiveness and robustness of the proposed approach over recently reported methods.